Data concerning the chemical and physical properties of carcinogenic N-nitroso compounds are collected. Specific emphases include: (a) the preparation of novel nitrosamines and their derivatives for chemical and biological studies; (b) the biological chemistry of nitrosamines, both in vivo and in microsomal systems, with special attention to the rate modifying effects of deuterium substitution; (c) mechanistic studies of N-nitrosation reactions of environmental interest, particularly those promoted by electrophilic species, including transition metal complexes. Possible implications of this work with respect to the overall goal of human cancer prevention will be considered.